A window of a vehicle gets foggy when an outdoor temperature is low and humidity is high. An auto defog system (ADS) has been provided in the vehicle recently, which uses a humidity sensor to sense whether fog occurs on the window and turns on an air conditioner to generate wind on the window to remove the fog.
However, the ADS is expensive and decreases fuel efficiency due to the use of an air conditioner.
In the winter season, fog on a vehicle window occurs due to a low dew point inside a vehicle when a temperature outside the window is low and indoor humidity is high. Further, when air blows toward the window while operating an air conditioner in a humid summer day, a temperature of the window is low, and outdoor humidity is high, the fog also occurs outside the window.
The fog occurring outside the window can be removed by operating a wiper, but the air conditioner still needs to be operated to remove the fog inside the window.
A current air conditioning apparatus is designed to automatically operate the air conditioner in a floor and defrost mode (mix mode) and a defrost only mode (DEF) to rapidly remove the fog.
However, when the air conditioner operates, fuel efficiency is degraded, and thus, passengers do not use the floor and defrost mode or the defrost only mode. However, when the air conditioner does not operate in the above modes, it is difficult to remove the excessive fog on the window.
As an evaluation result, the fog on the window easily occurs in a driver/passenger's body mode (vent mode), a driver/passenger's body and floor mode (Bi level mode), and a floor mode (FLR mode) under an air conditioner off condition, in which a considerable amount of fog occurs in the order of body and floor mode>body mode>floor mode.
The following Table 1 shows a distribution of air volume for each air direction mode and in the floor mode (FLR mode), some of air blows toward the window but in the body and floor mode (B/L) and the body mode (vent mode), the air does not blow toward a window. That is, the fog on the window may be effectively suppressed by blowing the air to the window.
TABLE 1Distribution of Air VolumeMODEFaceLegWindowVENT100%  0% 0%B/L65%35% 0%FLR10%65%25%MIX10%45%45%DEF10% 0%90%
However, the body mode (VENT) and the body and floor mode (B/L), which are frequently used at the time of mainly operating the air conditioner, generate fog outside the window when the air blows toward the window. Thus, the VENT mode and B/L mode may not blow the entire wind toward the window, but blows only a small amount of air to a leg when a large amount of air is sent to a window in the winter, therefore decreasing heating performance.
The matters described as the related art have been provided only for assisting in the understanding for the background of the present disclosure and should not be considered as corresponding to the related art known to those skilled in the art.